The present invention relates to an actuator for an orienting device for orienting a borehole apparatus in a borehole and to an orienting device comprised of the actuator. The orienting device includes an orienting mechanism actuated by longitudinal movement.
Directional drilling involves controlling the direction of a borehole as it is being drilled in order to drill along a predetermined path. It is often necessary to adjust the direction of the borehole frequently while directional drilling, either to accommodate a planned change in direction or to compensate for unintended or unwanted deflection of the borehole.
Directional drilling may involve the use of a drilling bit actuated by a downhole motor connected with the drill string and which is powered by the circulation of fluid, such as drilling mud, supplied from the surface. Typically, the downhole motor includes a bent housing or bent sub so that the resulting path drilled by the drilling bit is slightly curved. Further, the downhole motor actuates the drilling bit relative to the bent housing or bent sub and the drill string. In other words, the drill string itself need not be moved or rotated during the drilling operation in order to actuate the drilling bit.
The drilling operation will be intermittently interrupted in order to ascertain the path of the borehole in relation to the desired predetermined path. In the event that correction or adjustment of the path is required, the drill string may be rotated from the surface in order to rotate the bent motor housing or the bent sub downhole. This is possible due to the relatively rigid nature of a conventional drill string. Thus, rotation of the drill string from the surface orients the bent housing or bent sub in the desired direction to adjust the borehole towards the desired predetermined path.
However, coiled tubing may also be used for drilling operations such that the drill string is typically comprised of a single length of relatively flexible tubing which is inserted into the borehole. Various downhole tools, including a downhole motor and drilling bit, may be connected with the downhole end of the coiled tubing string. However, as a result of the nature of coiled tubing and the manner by which it is run into the borehole, it is not possible to rotate the bent housing or bent sub downhole, in order to adjust the direction of the borehole, by rotating the coiled tubing string from the surface.
As a result, various orienting devices or orienting subs have been developed for connection between the coiled tubing string and the bent housing or bent sub. These orienting devices are provided to rotate the bent housing or bent sub relative to the coiled tubing string in order to adjust the direction of the borehole. Typically, the orienting device rotates the bent housing or bent sub through a selected incremental amount in order to fix the angular orientation of the bend point in the bent housing or bent sub in relation to the axis of the borehole so that the borehole can be drilled along the predetermined path.
Several of these orienting devices are comprised of hydraulic systems connected to the surface for supply of the hydraulic fluid to actuate the device. For instance, U.S. Pat. No. 5,316,094 issued May 31, 1994 to Pringle and U.S. Pat. No. 5,894,896 issued Apr. 20, 1999 to Smith et. al. both describe an orienting device for use with coiled tubing for rotationally orientating a well tool to the proper direction in the well bore. The orienting device is comprised of a body or tubular housing, a mandrel rotatable within the body for providing rotation to the well tool and a hydraulic piston slidably positioned in the annulus between the body and the mandrel. The orienting device provides for the rotation of the mandrel within the body or housing in response to the longitudinal movement of the piston in the annulus.
In Pringle, a hydraulic control line is connected to a first side of the piston for moving the piston longitudinally in a first direction. A spring is provided against the second side of the piston for moving the piston longitudinally in an opposed second direction. The hydraulic control line is provided from the surface, through the coiled tubing to the orienting device to provide the hydraulic control fluid for operating the orienting device. Similarly, in Smith et. al., a flow path is provided for the selective delivery of pressurized hydraulic fluid to either side of the piston so that the mandrel may be rotated in either a clockwise or a counterclockwise direction or to both sides of the piston equally to maintain the piston in a fixed annular orientation. Further, the flow path is supplied with hydraulic fluid through two hydraulic lines which transfer fluid from the surface to the device with the lines alternating in function as either supply, relief or return lines.
Given the inherent disadvantages associated with the use of a hydraulic system including hydraulic lines from the surface for actuating the orienting device, various further orienting devices have been developed which are actuated by the fluid being conducted through the drill string, such as the drilling mud. For instance, U.S. Pat. No. 5,215,151 issued Jun. 1, 1993 to Smith et. al. and Sperry-Sun Drilling Services Technology Update, Winter 1995, entitled xe2x80x9cCoiled Tubing BHA Orienter for Directional and Horizontal Drillingxe2x80x9d each describe an orienting device or orienting sub which is actuated by the flow of the drilling mud through the device.
These orienting devices are located in the bottom hole assembly above the motor and are actuated by the pressure drop across, or the mud flow rate through, the bottom hole assembly including the orienting device. In particular, a flow path is provided through the orienting device for the circulation of the drilling fluid relatively unrestricted therethrough at all times. Further, the device is comprised of a drive piston which is exposed to the drilling fluid as it circulates through the device. When the drilling fluid pumps are on, the flow induced pressure drop acts across the drive piston of the device and drives it downwards against a helical cam, which results in the indexing of an output shaft of the device a predetermined increment of degrees. Upon cessation of the flow, the drive piston is biased by a spring to be driven upwards to reset the orienting device. Thus, the flow through the device may be cycled a desired number of times in order to achieve the desired indexing of the output shaft and the downhole tool connected thereto.
However, there is no positive indication provided to the operator at the surface that the orienting device has in fact cycled or indexed upon pumping the drilling fluid therethrough. Further, given the relatively unrestricted flow of the drilling fluid permitted through the orienting device, it has been found that a relatively high pressure of the drilling fluid is required within the device to act upon the drive piston and move it downwards to index the output shaft. To achieve this necessary actuating pressure, the flow of the drilling fluid through the bottom hole assembly, including the motor, may similarly be excessive resulting in unnecessary wear and potential damage to the bottom hole assembly and the motor.
As a result, the orienting device may be used with a companion device referred to as an equalizer sub. The equalizer sub is positioned in the bottom hole assembly between the orienting device and the motor. The equalizer sub includes a restrictor nozzle which is positioned in the flow path of the drilling fluid to provide a partial restriction to the flow therethrough. More particularly, the restrictor nozzle generates a differential pressure and creates a pressure drop with which to power the orienting device. The restrictor nozzle provides a sufficient back pressure in the orienting device to actuate the drive piston and drive it downwards without the associated increase in the mud flow rate through the motor. Further, the equalizer sub includes a vent port to allow the pressure to equalize between the bottom hole assembly and the borehole annulus when the pump is off, thus permitting the orienting device to be reset by a return spring.
For example, U.S. Pat. No. 5,311,952 issued May 17, 1994 to Eddison et. al. describes a reciprocating mandrel assembly mounted within a housing. A piston is mounted to the upper end of the mandrel assembly, while a nozzle is mounted onto the lower end of the mandrel assembly. The flow path of the drilling fluid is provided through the mandrel assembly from its upper to its lower end. Thus, the nozzle at the lower end provides a partial restriction of the flow path through the orienting device. Accordingly, when the drilling mud is pumped downwardly through the mandrel assembly, a pressure drop is created across the nozzle which generates a downward force on the piston mounted to the upper end of the mandrel assembly and drives the mandrel assembly to a lower position, thus indexing the device an incremental amount. Upon reducing the rate of mud flow through the mandrel assembly, the bias of a spring acts upon the mandrel assembly to return it to its upper position, thus further indexing the device a further incremental amount.
However, although it is advantageous to have a relatively high pressure drop while the bottom hole assembly is orienting, and thus the orienting device is doing the work, it is also advantageous to subsequently decrease the pressure drop to a lesser amount while drilling ahead with the downhole motor. These further orienting devices do not provide for a subsequent decrease in the pressure drop.
In addition, with these further orienting devices there continues to be no positive surface indication that the orienting device has in fact cycled or indexed upon pumping the drilling fluid therethrough. Further, although the restrictor nozzle or equalizer sub provide some protection to the motor against excessive mud flow rates, the surface pumps are often required to work harder to maintain the desired flow rate through the motor as a result of the presence of the restriction. Further, and as a result, particular care must be taken in selecting the amount of the restriction or size of the restrictor nozzle to ensure that the pressure within the drill string, and particularly the coiled tubing, above the orienting device is maintained at acceptable levels.
Thus, there remains a need in the industry for an improved orienting device for orienting a borehole apparatus in a borehole and for an improved actuator for the orienting device. Preferably, the improved actuator and orienting device relatively easily produce a pressure drop necessary to actuate or cycle the orienting device, while minimizing the associated disadvantages as discussed above. Further, the actuator and orienting device preferably cycle upon a relatively lower or lessened continuous pressure drop across the device as compared to other orienting devices, such as those described herein. Finally, there remains a need in the industry for an improved orienting device and for an improved actuator for the orienting device which preferably provide a positive surface indication that the orienting device has cycled.
The present invention relates to an actuator for a downhole apparatus or device which is actuated by longitudinal movement. The actuator may be used to actuate any such downhole apparatus or device, however, preferably, the downhole apparatus or device is an orienting device for orienting a borehole apparatus in a borehole.
More particularly, the present invention relates to an actuator for an orienting device for orienting a borehole apparatus in a borehole, wherein the orienting device preferably includes an orienting mechanism actuated by longitudinal movement. Further, the present invention relates to an orienting device comprised of the actuator, wherein the orienting device preferably includes an orienting mechanism actuated by longitudinal movement.
In addition, the actuator and the orienting device are preferably exposed to and actuated by a pressure of a fluid, preferably a fluid being circulated through the orienting device. In the preferred embodiment, the actuator and the orienting device are exposed to and actuated by the pressure of a drilling fluid. Further, the actuator and the orienting device are preferably actuated and cycle upon a relatively lower or reduced pressure of the fluid as compared to other orienting devices, such as those described above.
As well, the actuator and the orienting device of the within invention preferably provide a positive surface indication that the orienting device has fully cycled. In the preferred embodiment, the positive surface indication is provided by a visible or notable change in the pressure drop in the drilling fluid when actuated, which is observable at the surface by the operator.
Thus, in a first aspect of the invention, the invention is comprised of an actuator for an orienting device, wherein the orienting device is comprised of an orienting mechanism which is actuated by longitudinal movement, the actuator comprising:
(a) a housing having a first end and a second end;
(b) a fluid passageway extending through the housing from the first end to the second end;
(c) a longitudinally reciprocable piston positioned within and providing a first partial obstruction of the fluid passageway, for engagement with the orienting mechanism such that longitudinal movement of the piston actuates the orienting mechanism; and
(d) a flow restrictor positioned within and providing a second partial obstruction of the fluid passageway, the flow restrictor being associated with the piston such that the first partial obstruction is longitudinally aligned with the second partial obstruction for a portion of a longitudinal range of travel of the piston to provide a combined obstruction of the fluid passageway.
In a second aspect of the invention, the invention is comprised of an orienting device for orienting a borehole apparatus in a borehole, wherein the orienting device is comprised of an orienting mechanism which is actuated by longitudinal movement and an actuator for actuating the orienting mechanism, the actuator comprising:
(a) a housing having a first end and a second end;
(b) a fluid passageway extending through the housing from the first end to the second end;
(c) a longitudinally reciprocable piston positioned within and providing a first partial obstruction of the fluid passageway, for engagement with the orienting mechanism such that longitudinal movement of the piston actuates the orienting mechanism; and
(d) a flow restrictor positioned within and providing a second partial obstruction of the fluid passageway, the flow restrictor being associated with the piston such that the first partial obstruction is longitudinally aligned with the second partial obstruction for a portion of a longitudinal range of travel of the piston to provide a combined obstruction of the fluid passageway.
In both the first and second aspects of the invention, the actuator and the orienting device may be used for any application in which the orientation or direction of a borehole apparatus is desired to be controlled or adjusted within the borehole. However, the actuator and the orienting device have particular application for use with coiled tubing. Particularly, the actuator and the orienting device have particular application for coiled tubing drilling for drilling directional and horizontal wells. In this instance, the actuator and the orienting device are preferably included within or comprise a bottom hole assembly connected downhole with a coiled tubing string.
Further, the orienting device may be used to orient any borehole apparatus in the borehole which comprises all or a portion of the bottom hole assembly. However, preferably, the borehole apparatus is comprised of a downhole motor for drilling the borehole, wherein the downhole motor is connected with a drilling bit driven by the downhole motor. The downhole motor comprises or is included within the bottom hole assembly and is connected with the drill string such that it is powered by the circulation of fluid, such as drilling mud, supplied from the surface through the drill string, preferably a coiled tubing string.
In addition, the borehole apparatus is preferably comprised of a downhole motor including or connected with a bent housing or bent sub such that the drilling bit is driven by the downhole motor relative to the bent housing or bent sub. In this instance, the orienting device of the within invention is connected or associated with the borehole apparatus, being the downhole motor, such that actuation of the orienting device results in the orienting or rotation of the downhole motor including the bent housing or bent sub. As a result, the direction of the drilling bit, and the resulting borehole, may be adjusted in the borehole. To achieve this function, the orienting device of the within invention is connected between the coiled tubing string and the downhole motor.
Further, the orienting device may be any type of orienting device, mechanism or tool, and the orienting device may have any structure or configuration, compatible with and capable of being actuated by the actuator of the within invention as described herein. More particularly, the orienting device is comprised of an orienting mechanism which is actuated by longitudinal movement. Thus, the orienting device of the within invention may be any type of orienting device, mechanism or tool comprised of an orienting mechanism actuated by longitudinal movement.
The orienting mechanism of the orienting device may orient the borehole apparatus in any manner and by any degree or increments. In addition, the orienting device may orient the borehole apparatus by rotation in a clockwise direction, counterclockwise direction or both. However, in the preferred embodiment, the orienting device indexes the borehole apparatus a predetermined increment in a clockwise direction (when viewed from above) every pump cycle, i.e. every time the pump pumping or circulating the drilling fluid to the downhole motor is powered up and powered down to provide a complete cycle.
Further, the indexing may occur at any time during the pump cycle, i.e., during the powering up of the pump, the powering down of the pump or both, to provide the predetermined indexing increment. However, in the preferred embodiment, the orienting device indexes the borehole apparatus the predetermined increment upon the powering up of the pump to provide the necessary actuation pressure to drive or actuate the actuator. When the pump is powered down and the pressure is decreased to a level less than the actuation pressure, the orienting device simply resets itself in preparation for the next pump cycle. No further indexing occurs during the powering down of the pump.
The housing of the actuator may be comprised of a single integral tubular element or member defining the fluid passageway therethrough or it may be comprised of two or more such tubular elements or members connected, attached, mounted or otherwise affixed together, permanently or detachably, to provide the housing. Further, the housing may be connected, attached, mounted or otherwise affixed with the orienting device either permanently or detachably. However, in the preferred embodiment, the actuator housing is formed integrally with the orienting device.
Similarly, the actuator and the orienting device as a unit may be formed integrally with the other components of the bottom hole assembly or it may be connected, attached, mounted or otherwise affixed with the other components of the bottom hole assembly either permanently or detachably. More particularly, the actuator and the orienting device as a unit may be formed integrally with the borehole apparatus or it may be connected, attached, mounted or otherwise affixed with the borehole apparatus either permanently or detachably.
Finally, as discussed above, the actuator and the orienting device may be connected into the bottom hole assembly at any position or location therein permitting the functioning of the orienting device. However, preferably, the actuator and the orienting device as a unit are positioned or located between the drill string, preferably a coiled tubing string, and the borehole apparatus to be oriented, preferably a downhole motor. In this case, each of the uphole end and the downhole end of the combined actuator and orienting device may be directly or indirectly connected, attached, mounted or otherwise affixed with the coiled tubing string and the downhole motor respectively.
Thus, the bottom hole assembly may include any number of further downhole devices, apparatuses or tools. For instance, the bottom hole assembly typically includes one or more Measurement-While-Drilling (xe2x80x9cMWDxe2x80x9d) devices, which are preferably connected into the bottom hole assembly between the orienting device and the downhole motor. Further, where desirable, the bottom hole assembly may include a dump or equalizer sub as described above. In this case, the dump or equalizer sub is also preferably connected into the bottom hole assembly between the orienting device and the downhole motor.
As indicated, the actuator is comprised of a longitudinally reciprocable piston positioned within the fluid passageway extending through the housing. Thus, the piston is exposed to the fluid within the fluid passageway. Further, the piston provides a first partial obstruction of the fluid passageway such that a pressure of the fluid within the fluid passageway may act upon the piston to cause the longitudinal movement of the piston within the housing.
The flow restrictor is similarly positioned within the fluid passageway and provides a second partial obstruction of the fluid passageway. The flow restrictor may similarly be longitudinally movable or reciprocable within the fluid passageway. However, preferably, the flow restrictor is at a fixed longitudinal position in the fluid passageway. As a result, in the preferred embodiment, the piston is longitudinally movable relative to the fixed longitudinal position of the flow restrictor.
Further, the flow restrictor and the piston are associated such that the first partial obstruction is longitudinally aligned with the second partial obstruction for a portion of a longitudinal range of travel of the piston to provide a combined obstruction of the fluid passageway. The range of travel of the piston extends between a first position of the piston and a second position of the piston. The piston may actuate the orienting mechanism by moving toward either the first position or the second position. However, preferably, the piston actuates the orienting mechanism by moving toward the second position. Further, the combined obstruction is preferably timed so that the fluid flow is restricted by the combined obstruction until the orientation of the bottom hole assembly, and particularly the borehole apparatus, has been completed, i.e., while the greatest work is being done by the orienting device.
Specifically, in the preferred embodiment, the first partial obstruction is longitudinally aligned with the second partial obstruction when the piston is at the first position. Movement of the piston toward the second position moves the first partial obstruction out of longitudinal alignment with the second partial obstruction.
The combined obstruction provided by the longitudinal alignment of the first and second partial obstructions may partially obstruct the fluid passageway, while still permitting the passage or movement of an amount of a fluid therethrough. However, preferably, the combined obstruction obstructs the fluid passageway substantially completely so that a fluid is substantially blocked from moving through the fluid passageway when the first partial obstruction is aligned with the second partial obstruction.
The flow restrictor may have any shape or configuration and be comprised of any mechanism, structure or device providing the second partial obstruction. In other words, the flow restrictor partially obstructs the fluid passageway, while permitting an amount of fluid to pass therethrough. The piston may have any shape or configuration and may be comprised of any hydraulically actuated mechanism, structure or device reciprocable within the fluid passageway and providing the first partial obstruction. In other words, the piston also partially obstructs the fluid passageway, while permitting an amount of fluid to pass therethrough. Finally, the flow restrictor and the piston must be selected to be compatible such that the first partial obstruction is capable of being longitudinally aligned with the second partial obstruction to provide the combined obstruction of the fluid passageway.
Each of the first and second partial obstructions may obstruct the fluid passageway in any manner. For instance, upon cross-section of the combined obstruction, each of the first and second partial obstructions may contribute to the combined obstruction and be related to each other or positioned within the fluid passageway relative to each other in any manner. Thus, the piston and the flow restrictor may be related to each other or positioned within the fluid passageway relative to each other in any manner. However, preferably, one of the piston and the flow restrictor provides an outer partial obstruction, while the other of the piston and the flow restrictor provides an inner partial obstruction. Thus, the inner partial obstruction fits or is positioned within the outer partial obstruction to provide the combined obstruction. In the preferred embodiment, the piston is comprised of an annular sleeve having an internal bore and the flow restrictor is positioned within the internal bore when the first partial obstruction is aligned with the second partial obstruction.